Differential and reduction gear means for road vehicle axles



March 13, 1956 R, H. wHON 2,737,829

DIFFERENTIAL AND REDUCTION GEAR MEANS FOR ROAD VEHICLE AXLES Filed Feb. 4, 1954 mfom/.Fys

United States Patent O DIFFERENTIAL AND REDUCTION AGEAR MEANS v FOR ROAD VEHICLEAXLES Ronald H. Wilson, Horsforth, near Leeds, England, as-

Ais'ignol' -to Kirkstzill Forge Engineering Limited, Leeds, iEngland .Application February 4, 1954, SerialNo. 408,153

Claims priority, application Great Britain February 1-7, 1953 6 Claims. (Cl. 74-694) YThis `invention relates to driven axles for motor road vehicles of the type, described `in U. `S. Patent No. 2,548,236, .comprising an axle casing, a.pair of live vaxles each `'driving one of the road wheels, and a .reduction gearingconstituted by gear trains which kdrive :the .t-,road wheels :at .substantially equal torque while allowing dif- Aferential movement thereof.

The .axle described in U. S. Patent No. `2,648,236 includesa rst reduction stage in the axle `casing, the `second reduction stage consisting of a pair vof gear trains, also .intthe axle casing, and each comprisingthree componente, viz. a gear wheel, an internally .toothed ,annulus and .a,pinion carrier, one component of the iirst .gear train being ydriven from the rst reduction stage,another component thereof driving one of the .live axles and -t'he component thereof driving 'the ygear wheel of `the second ,gear train, and a vsecond ycomponent of .the-second ,gear train Vbeing Viixed, or .adapted 4to be Yiixed, `to the faxle cas'ing,and the third component thereof driving the other live axle.

There are, however, limits to the overall .reduction which "is obtainable with the axle described in.S. Patent No. l2,648,236, and the present invention aims to provide .an axle which, whether or notitincludes aiirst `reduction Stage, utillgive a much larger overall reduction.

The Iinvention provides a driven axle for a motor road vehicle of the above type, in which the reduction ,gearing comprises three gear trains, each constituted 'by an internally toothed annulus, a pinion carrier 'and a `center gear Wheel, namely an inner epicyclic geartrain Vin the 'axlefcasing the center gear Vwheel of which iis 'adapted yto b'efdriven from the transmission of thevehicle, and a pair oftouter fgear trains of similar tooth ratio, thecenter `gear wheel of one *outer gear Atrain being coupled 'lfor rot-'ation with the annulus of the inner epicyclic fgear Str-fain, its annulus being fixed and its vpinion carrier Idriving one road wheel and the center gear wheel of the other outer gear trainbeing coupled for rotation with the pinion carrier of the inner Vepicyclic gear train, its zpinion carrier being Xed and its annulus driving the other road wheel.

Preferably the axle includes a bevel .drive as varst-re duction stage, but, in appropriate cases, a Wormer-other suitable drive may be used asV an alternative. .As noted, however, a 'first reduction stage is not `essential and :the center gear wheel of the inner epicyclic ,gear traintmay be driven lfrom the transmission shaft of the vehicle through gearing havin'ga 1:41 ratio. "The outer gear trains may 'be disposed in the Wheel hubs but, aas an alternative, they may be disposed in the axle casing and drive their associated road wheels through live axles extending from the axle casing to the road wheels.

One specic embodiment of the invention, as applied to the driven rear axle of a motor road vehicle, will now be described in more detail by way of example, with reference to the accompanying drawing. It will be appreciated, however, that the invention is also applicable to driven front axles and to steering and driven axles 2,737,829 Patented Mar. 13, 1956 2 -since, .in the .latter case, Vuniversal joints may be incor- .porated .in the llive l axles.

The rear axle shown in .the drawing, which is adiagrammatic plan `view, partly insectionfcomprises an axle vcasing 1.from which-project the usual axlerarms A2, A3 containingrthe live axles 4, v5 for `transmitting the vdrivefrom theaxlecasing to the lroad wheels, the hubs of whichare shown at-6 and 7. In the axle casing Ais a rst 4reduction stage, driven from the `transmission yshaft 13 and consti- 'tuted .by Abevel vgears t8, I9 ygiving a .reduction of r1.25/1, Vand Van inner .epicyc'lic l.gear train A1l). Two outer .gear vtrains .1-1, 12 are provided, Vone Vineach wheel hub, `the gear train 11 being an epicyclic gear train and 'the gear Ltrain 12 a reduction train. .The center gear wheels of `thegear .trains ,10, 1'1, 12 are .identified yby the references S1, S2, yS3 respectively, the pinion carriers by P1, Pz, :R3 Vand the :annuli yby Ai, .A2, A3.

.All of the three fgear trains are 3 to .l trains, i. e. ett/8:3 where A is the -number of teeth on .the annulus and S the number of =teeth on the center gear wheel. VConveniently the annulus;V of each `gear train has 72 teeth and its center :gear wheel .24 teeth, and Iits pinion carrier carries three pinions 20, -zeach having 24 teeth.

ICC

iThe driven bevel gear 9 of thefirst reduction stage is Y formed on, or may bebolted to, a sleeve 14 carrying the sun wheel Si of the central epicyclicgear .train 10 Vand supported on bearings Y15. The pinion carrier P1 -of ,the central epicyclictgear trainfhas an oiset extension, shown diagrammatically .at IB, and. attached, e. g. Vby splines, tothe olside'liveaxle 5, which extends through thesleeve '14 and carries the centergear wheel 4S2 of the oiiside vhub .reduction gear train. The annulusfAi of -the innerepi- .yclicgear .train has an offset-extension `1'9 supported 4by bearings .I6 and 17 and attached, fi. e. by splines,to :the near side ilive axle y4, which carries .the center gear wheel S3 of the .near side Ahub .reduction Agear train.

Ina simple epicyclic :train the sun wheel torque .plus the annulus torque is always equal to the pinion carrier torque.Y if therefore unit torque is appliedin a clockwise direction to the r'iVenbevel gear .9 of the rst reduction stage, the near side-live axle 4 '(coupledto the annulus A1 ofthe linner train) will experience a torqueof `3 .ina counter-.clockwise direction and the oisidelive axle f5 (coupled 'to the Ipinion carrier R1 of the .inner train) a torque .of 4 Vin 'a clockwise direction.

The ,pinions f2() of the. near side .hub .reduction ,gear train aremounted on bolts 21 iixed tothe near .side wheel hub '6, which 'thus constitutes the ,pinion carrier 'P3 of the near side train.1`2, and its annulus ,A3 is `'fixed .to `theaxle arm?. *The near sideroad wheel accordingly experiences a torque of Al2 Ain -a counter-clockwise direction. The pinions Z0 of Athe oisiide huh .reduction gear :train are mounted on bolts 22 fixed to the axle arm 3, which `thus constitutes 'the pinion carrier VKPz. of the `near side ytrain .11, so 'that this gear train functions as a straight reduction gear, and its annulus A2 is integral with the oiside wheel hub'?. The offside road wheel therefore also experiences a torque of 12 in a counter-clockwise direction.

h'e total y'output torque "is thus 24 so that 'the second stage reduction -is '2451. As the bevel gearing vgives a reduction -of '1.25:'-1 the overall reduction 4is 30:1.

TIlhe arrangement described :thus gives the large reduction required withoutroecupyingiundue'spaee. The symmetrical position of the input shaft 13 is an advantage and the three gear trains are all readily removable for servicing.

What I claim as my invention and desire to secure by Letters Patent is:

l. In a driven axle for a motor road vehicle including an axle casing and a pair of wheel hubs, reduction gearing for driving said wheel hubs from a transmission shaft at substantially equal torque while permitting of differential movement thereof, comprising an inner epicyclic gear train in the axle casing and two outer gear trains one of which is an epicyclic gear train and the other of which is a reduction gear train, each of said three gear trains including a center gear wheel, an internally toothed annulus, a pinion carrier and pinions on said carrier meshing with said center gear wheel and with said annulus, the center gear wheel of said inner epicyclic gear train being adapted to be driven from said transmission shaft, the annulus of the outer epicyclic gear train and the pinion carrier of the outer reduction gear train being held fixed, the pinion carrier of the outer epicyclic gear train driving one wheel hub and the annulus of the outer reduction gear train driving the other wheel hub, means coupling the center gear wheel of said outer epicyclic gear train for rotation with the annulus of the inner epicyclic gear train, and means coupling the center gear wheel of the said outer reduction gear train for rotation with the pinion carrier of the inner epicyclic gear train.

2. In a driven axle for a motor road vehicle including an axle casing and a pair of wheel hubs, reduction gearing for driving said Wheel hubs from a transmission shaft at substantially equal torque while permitting of differential movement thereof, including a rst reduction stage in the axle casing and a second reduction stage, said second reduction stage comprising an inner epicyclic gear train in the axle casing and two outer gear trains one of which is an epicyclic gear train and the other of which is a reduction gear train, each of said three gear trains including a center gear wheel, an internally toothed annulus, a pinion carrier and pinions on said carrier meshing with said center gear wheel and with said annulus, the center gear wheel of said inner epicyclic gear train being adapted to be driven from said transmission shaft, through said rst reduction stage, the annulus of the outer epicyclic gear train and the pinion carrier of the outer reduction gear train being held fixed, the pinion carrier of the outer epicyclic gear train driving one wheel hub and the annulus of the outer reduction gear train driving the other wheel hub, means coupling the center gear wheel of said outer epicyclic gear train for rotation with the annulus of the inner epicyclic gear train, and means coupling the center gear wheel of said outer reduction gear train for rotation with the pinion carrier of the inner epicyclic gear train.

3. In a driven axle for a motor road vehicle including an axle casing and a pair of wheel hubs, reduction gearing for driving said wheel hubs from a transmission shaft at substantially equal torque while permitting of differential movement thereof, including a rst reduction stage in the axle casing constituted by bevel gearing and a second reduction stage, said second reduction stage comprising an inner epicyclic gear train in the axle casing and two outer gear trains one of which is an epicyclic gear train and the other of which is a reduction gear train, each of said three gear trains including a center gear wheel, an internally toothed annulus, a pinion carrier and pinions on said carrier meshing with said center gear wheel and with said annulus, the center gear wheel of said inner epicyclic gear train being adapted to be driven from said transmission shaft through said first reduction stage, the annulus of the outer epicyclic gear train and the pinion carrier of the outer reduction gear train being held fixed, the pinion carrier of the outer epicyclic gear train driving one wheel hub and the annulus of the outer reduction gear train driving the other wheel hub, means coupling the center gear wheel of said outer epicyclic gear train for rotation with the annulus of the inner epicyclic gear train, and means coupling the center gear wheel of said outer reduction gear train for rotation with the pinion carrier of the inner epicyclic gear train.

4. In a driven axle for a motor road vehicle comprising an axle casing, a pair of wheel hubs and first and second live axles, reduction gearing for driving said wheel hubs from a transmission shaft at substantially equal torque while permitting of differential movement thereof, and including an inner epicyclic gear train in the axle casing, said inner epicyclic train having a center gear wheel driven from said transmission shaft, a pinion carrier fixed to the first live axle and an annulus fixed to the second live axle, and two gear trains, each disposed within one of the wheel hubs and each including a center gear wheel fixed to one of the live axles, a pinion carrier, pinions on the pinion carrier meshing with the center wheel and an internally toothed annulus meshing with said pinions, the outer gear train driven by said rst live axle having its pinion carrier xed and its annulus driving the associated wheel hub, and vthe other outer gear train having its annulus fixed and its planet carrier driving the associated wheel hub.

5. In a driven axle for a motor road vehicle comprising an axle casing, a pair of wheel hubs and first and second live axles, reduction gearing for driving said wheel hubs from a transmission shaft at substantially equal torque while permitting of differential movement thereof, and comprising a first reduction stage in the axle casing and a second reduction stage including an inner epicyclic gear train in the axle casing, said inner epicyclic train having a center gear wheel driven from said transmission shaft through said first reduction stage, a pinion carrier fixed to the first live axle and an annulus fixed to the second live axle, and two gear trains, each disposed within one of the wheel hubs and each including a center gear wheel fixed to one of the live axles, a pinion carrier, pinions on the pinion carrier meshing with the center wheel and an internally toothed annulus meshing with said pinions, the outer gear train driven by said first live axle having its pinion carrier fixed and its annulus driving the associated wheel hub, and the other outer gear train having its annulus fixed and its planet carrier driving the associated wheel hub.

6. In a driven axle for a motor road vehicle comprising an axle casing, a pair of wheel hubs and first and second live axles, reduction gearing for driving said wheel hubs from a transmission shaft at substantially equal torque while permitting of differential movement thereof, as claimed in claim 5, wherein said first reduction stage is constituted by bevel gearing.

References Cited in the file of this patent UNITED STATES PATENTS 876,501 sfeinhauer Jan. 14, 1908 1,264,748 Apple Apr. 30, 1918 1,327,206 Jackson Jan. 6, 1920 1,467,939 Knap Sept. 11, 1923 1,585,141 Foote May 18, 1926 2,648,236 Wilson Aug. 11, 1953 FOREIGN PATENTS v 657,264 Great Britain -g Sept. 12, 1951 

